This invention relates generally to threaded caps and containers. More particularly, the invention relates to caps and containers that are tamper proof in the sense that any tampering with the cap when sealed to the container is clearly visible.
Tamper proof caps are used in food and drug packaging to indicate to a prospective purchaser whether the cap on a container has been removed and replaced. These caps come in a variety of types, as illustrated in the following patents.
U.S. Pat. No. 4,337,870 to Keeler discloses a threaded cap joined to a sealing ring by frangible bridges. The ring includes ratchet segments that engage pawl teeth on the container neck with the cap closed. To open the container, the cap is turned counterclockwise with sufficient force to shear the bridges.
U.S Pat. No. 4,418,828 to Wilde et al. discloses a cap having a threaded skirt to which is attached, by a fracturable area, a pilfer band. As the cap is unthreaded, the band catches against the bottom surface of a locking ring on the container neck. Continued unthreading of the cap causes the fracturable area to fracture and the pilfer band to tear free of the skirt portion.
U.S. Pat. No. 4,480,761 to Aichinger discloses a cap similar in design to Wilde et al. The cap includes a closure portion to which is joined a guarantee strip by rupturable web portions. With the cap in its closed position, the guarantee strip engages the bottom of a container neck ring. Unscrewing the cap causes the strip to tear away from the closure portion, indicating that the cap has been removed.
U.S. Pat. No. 4,550,845 to Guala describes a bottle closure having a cap portion and a collar portion joined to the cap portion at a line of weakness. The collar portion has internal teeth that engage complementary teeth on the bottleneck with the closure in the closed position. When the cap is unscrewed, the collar is separated therefrom at the line of weakness and remains on the bottleneck.
U.S. Pat. No. 4,646,926 to Agbay et al describes a screw-on cap held in place on a container by a rotary safety ring. The ring must be aligned with the cap on one angular position and pushed downwardly away from the cap before one can remove the cap from the container. A tear tab is attached to the container neck below the ring to prevent the ring from being lowered. Thus a missing tear tab indicates that the bottle has been opened or tampered with.
U.S. Pat. No. 4,572,388 to Luker et al discloses a cap having a threaded upper skirt connected to a lower tamper indicating band by breakable bridge members. In one of the embodiments shown, the band has stop segments connected to its the lower edge. As the cap is threaded onto the container, the stop segments swing inwardly to pass over ratchet teeth on the container neck. Upon rotation of the cap in an unthreading direction, the stop segments engage the ratchet teeth to prevent further rotation of the band. Further rotation of the upper skirt causes the breakable members to fracture, allowing the cap to be removed while the band remains on the neck.
While these various caps have generally worked, they have a number of drawbacks. For one, they are expensive to mount. Caps with bottom rings require special machinery for proper mounting. For another, their protection can be circumvented. A removed cap can be replaced on a container and positioned over its sealing ring or band so as to appear to have been never removed.
The present invention has neither of these drawbacks. The cap can be mounted in a customary manner, and yet its removal and replacement are readily evident.